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Title: Site Campbell, BIOLOGY, 7th Edition Book Title: Biology Book Author: Campbell Location on Home > 15: The Chromosomal Basis of Site: Inheritance > Chapter Quiz Submitted: March 8, 2008 at 2:57 PM (EST) 98% Correct of 40 questions 39 correct: 1 incorrect: 98% 3% More information about scoring 1. The chromosome theory of inheritance states that _____. (Concept 15.1 ) Your Answer: The first, second, and third answers are correct. Correct. The theory encompasses these three basic elements. 2. Drosophila is a useful organism for genetic studies for all of the following reasons except _____. (Concept 15.1 ) Your Answer: They have a long generation time. Correct. Drosophila actually has a short generation time, making it feasible to carry out experiments that involve multiple generations. 3. Wild type refers to _____. (Concept 15.1 ) Your Answer: the most common phenotype in the natural population Correct. The wild type is the phenotype most often seen in the wild. 4. Which of the following statements about Thomas Hunt Morgan's experiments with white-eyed mutant flies is incorrect? (Concept 15.1 ) Your Answer: Among the F2 progeny, half of the females had white eyes. Correct. This is the incorrect statement. All of the F 2 females had red eyes. 5. If two genes are linked, _____. (Concept 15.2 Your Answer: they are on the same chromosome Correct. Genes located on the same chromosome are inherited together and are said to be linked. ) 6. In a particular species of mammal, black hair (B) is dominant to green hair (b), and red eyes (R) are dominant to white eyes (r). When a BbRr individual is mated with a bbrr individual, offspring are produced in a ratio of 5 black hair and red eyes:5 green hair and white eyes:1 black hair and white eyes:1 green hair and red eyes. Which of these explanations accounts for this ratio? (Concept 15.2 ) Your Answer: The genes for hair color and eye color are linked. Correct. This explains why the parental types occur more often than would be expected if the traits assorted at random. 7. A gray-bodied, vestigial-winged fly is crossed with a black-bodied, normalwinged fly. The F1 progeny is testcrossed. Among the resulting offspring, _____ is a parental type, and _____ is a recombinant type. (Concept 15.2 ) Your Answer: black-bodied, normal-winged ... black-bodied, vestigialwinged Correct. The two parental types are gray-bodied, vestigial-winged and black-bodied, normal-winged, and the two recombinant types are graybodied, normal-winged and black-bodied, vestigial-winged. 8. You perform a testcross using F1 dihybrid flies. If, in the resulting offspring, the percentages of parental and recombinant offspring are about the same, this would indicate that the two genes are _____. (Concept 15.2 ) Your Answer: unlinked Correct. Two genes on different chromosomes assort independently. 9. The recombination frequency between two gene loci is _____. (Concept 15.2 ) Your Answer: greater as the distance between the two loci increases Correct. The farther apart two genes are, the higher the probability that a crossover will occur between them, and therefore the higher the recombination frequency. 10. Four genes (A, B, C, and D) are on the same chromosome. The recombination frequencies are as follows: A-B: 19%; B-C: 14%; A-C: 5%; B-D: 2%; A-D: 21%; C-D: 16%. Based on this information, which sequence of genes is correct? (Concept 15.2 Your Answer: ACBD Correct. C must lie between A and B (5 +14 = 19). Similarly, D must be beyond B to be 21 units from A and 2 units from B. ) 11. In question 6, the observed distribution of offspring was as follows: blackred 1,070; black-white 177; green-red 180; green-white 1,072. Based on these data, what is the recombination frequency? (Concept 15.2 Your Answer: approximately 14% Correct. 177 + 180 = 357 recombinants. 357 recombinants/2,499 total offspring x 100 = 14% (approximately). ) 12. A linkage map _____. (Concept 15.2 ) Your Answer: orders genes on a chromosome based on recombination frequencies Correct. A linkage map presents the correct order of genes on the chromosome, although it is not necessarily an accurate representation of the actual distances between genes. 13. Because the frequency of crossing over is not uniform along the length of a chromosome, _____. (Concept 15.2 ) Your Answer: map units do not necessarily correlate to physical distances along the chromosome Correct. Map units reflect recombination frequency, but not physical distance. 14. Linked genes can be separated by anywhere from _____ to _____ centimorgans. (Concept 15.2 Your Answer: 0 ... 50 Correct. Centimorgans reflect recombination frequency. A distance of 0 centimorgans indicates that the genes are perfectly linked (that is, no recombination occurs between them), and a distance of 50 centimorgans indicates that they are unlinked and assort independently. ) 15. What is the probability that a male will inherit an X-linked recessive allele from his father? (Concept 15.3 Your Answer: 0% Correct. A male receives a Y chromosome from his father, not an X. ) 16. In an X-linked, or sex-linked, trait, it is the contribution of _____ that determines whether a son will display the trait. (Concept 15.3 Your Answer: the mother Correct. The son receives his single X chromosome from his mother and the Y from his father. ) 17. If a mother is heterozygous for a recessive sex-linked trait and her husband has the dominant allele, which one of the following is true about the probabilities for their children? (Concept 15.3 ) Your Answer: Half of their sons will have the recessive trait. Correct. All the sons will receive Y chromosomes from their father. The X must come from the heterozygous mother; therefore, each son has a 50% chance of inheriting the recessive allele. 18. In werewolves, pointy ears (P) is dominant over round ears (p). The gene is on the X chromosome. (Sex determination in werewolves is the same as for "other" humans.) A certain female werewolf has pointy ears even though her father had round ears. What percentage of her sons will have round ears if she marries a werewolf with round ears? (Concept 15.3 ) Your Answer: 50% Correct. The female werewolf must be heterozygous, because her father has round ears. Each of her sons has a 50% chance of inheriting the round allele. 19. A woman is red-green color-blind. What can we conclude, if anything, about her father? (Concept 15.3 ) Your Answer: He is red-green color-blind. Correct. For the woman to be affected with this sex-linked recessive trait, she must be homozygous; therefore, she must have received a recessive allele from her father. The father's single X must have the recessive allele. 20. A woman is a carrier for red-green color blindness, a sex-linked trait. Her husband is normal (not color-blind) for this trait. What are the chances that their newborn daughter will be red-green color-blind? (Concept 15.3 ) Your Answer: 0% Correct. The daughter must receive one of her X chromosomes from her normal father and will not be color-blind. 21. Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who die usually before the age of 20. Why is this disorder almost never seen in girls? (Concept 15.3 Your Answer: To express an X-linked recessive allele, a female must have two copies of the allele. Correct. Moreover, males carrying the allele have less of an opportunity to have offspring. ) 22. Hemophilia is a sex-linked disorder. The daughter of a father with hemophilia and a carrier mother has a _____ probability of having hemophilia. (Concept 15.3 Your Answer: 50% Correct. The mother is XHXh, and the father is XhY. The daughter must receive Xh from the father and has a 50% chance of receiving X h from the mother. ) 23. Queen Victoria was a carrier of a recessive sex-linked allele for hemophilia. Which one of the following possibilities could explain the presence of the hemophilia allele in her genotype? (Concept 15.3 Your Answer: Either her mother was a carrier or her father had hemophilia. Correct. Queen Victoria must have had the hemophilia allele on one of her ) X chromosomes. Either her mother was a carrier or her father was affected. 24. In a certain fish, fin rays (supporting structures for the fins) can be either bony or soft in adult fish. Sex linkage in a fish is similar to that in humans. What evidence would most strongly support the idea that the ray locus is on the X chromosome? (Concept 15.3 ) Your Answer: Matings of soft ray males and bony ray females give different results from the matings of bony ray males and soft ray females. Correct. Genes affecting sex-linked traits will give particular sex ratios in the offspring, and reciprocal crosses (males with the dominant trait crossed with females with the recessive trait, and males with the recessive trait crossed with females with the dominant trait) would not have the same results. 25. A genetic defect in humans results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way: A woman with this defect typically has small patches of skin with sweat glands and other patches without sweat glands. In women, the pattern of sweat-gland distribution can best be explained by _____. (Concept 15.3 Your Answer: X chromosome inactivation Correct. This pattern suggests that a gene on the X chromosome is involved in the production of sweat glands. If a female has one X chromosome that directs sweat-gland production and one that does not, then she will have patches both with and without sweat glands. ) 26. With a microscope, you examine some somatic cells from a woman and notice that each nucleus has two Barr bodies. What can you infer about the sex chromosomes in this individual? (Concept 15.3 Your Answer: She is XXX. Correct. Inactive X chromosomes in the cells of a female condense into compact objects known as Barr bodies. All X chromosomes in excess of 1 are inactivated. ) 27. During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____. (Concept 15.4 ) Your Answer: nondisjunction Correct. In nondisjunction, chromosomes fail to separate properly at meiosis. 28. In Klinefelter syndrome, individuals are phenotypically male, but they are tall and thin, have a female-like development of the hips and breasts, and have testes that remain in the abdomen instead of descending into the scrotum. The cells of Klinefelter individuals have two X chromosomes and one Y (they are XXY instead of XY). That is, Klinefelter syndrome is a(n) _____. (Concept 15.4 Your Answer: aneuploidy Correct. Aneuploidy is a chromosomal condition in which one or more chromosomes are present in extra copies or are deficient in number. ) 29. Cells that have more than two complete sets of chromosomes are termed _____. (Concept 15.4 Your Answer: polyploid Correct. Some organisms have more than two complete sets of chromosomes and are called polyploid. ) 30. _____ is usually less severe than _____, and _____ species have been observed in plants, fish, amphibians, and even mammals. (Concept 15.5 ) Your Answer: Polyploidy ... aneuploidy ... polyploid Correct. Polyploidy appears to disrupt genetic balance less than aneuploidy, and it has been observed among animals and especially plants. 31. Gene A is normally found on chromosome number 15 in humans. If amniocentesis reveals fetal cells containing gene A on chromosome 17, but not on 15, the best explanation would be that _____. (Concept 15.4 ) Your Answer: translocation occurred Correct. Fragments produced by chromosomal breakage may join nonhomologous chromosomes, a rearrangement known as a translocation. 32. The exchange of segments between nonhomologous chromosomes is called _____. (Concept 15.4 Your Answer: translocation Correct. Fragments produced by chromosomal breakage may join nonhomologous chromosomes, a rearrangement known as a translocation. ) 33. Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16? (Concept 15.4 ) Your Answer: Extra copies of the other chromosomes are probably fatal to the developing embryo. Correct. Nearly all trisomies have lethal effects. 34. When a person has Down syndrome, he or she has an extra chromosome 21. Therefore, Down syndrome is a kind of _____ and results from _____. (Concept 15.4 ) Your Answer: aneuploidy ... nondisjunction of chromosome 21 during meiosis I Correct. One aneuploid condition, Down syndrome, is the result of an extra chromosome 21. 35. A person with two X chromosomes and one Y chromosome would appear to be _____. (Concept 15.4 Your Answer: male Correct. The presence of the Y chromosome determines maleness in humans. A male with an extra X chromosome has Klinefelter syndrome. ) 36. Which one of the following is the only known viable human monosomy? (Concept 15.4 Your Answer: XO Correct. Turner's syndrome, or XO, is the only viable human monosomy. ) 37. Which type of chromosomal alteration is responsible for the disorder cri du chat? (Concept 15.4 Your Answer: deletion Correct. A specific deletion from chromosome 5 leads to this disorder, which is characterized by mental retardation, small head and unusual facial features, and a cry that sounds like a distressed cat. ) 38. Which of the following statements about genomic imprinting is incorrect? (Concept 15.5 ) Your Answer: It silences the expression of certain genes in females, but not in males. Correct. Imprinting equally affects gene expression in males and females. 39. Both chloroplasts and mitochondria _____. (Concept 15.5 Your Answer: carry extranuclear genes ) Correct. Both chloroplasts and mitochondria carry extranuclear genes. 40. It is proposed that a certain disorder affecting the inner ear is caused by mitochondrial DNA. Which of the following observations would be the most decisive evidence against this idea? (Concept 15.5 ) Your Answer: Mothers pass the disorder on to their offspring, but fathers do not. Correct Answer: Fathers with the disorder pass it on to all their children, but mothers with the disorder do not pass it along. No. This would support the mitochondrial inheritance of this condition.

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